Rheostat



J'une 16, 1925.

' s. E. JACOBS ET AL RHEOSTAT Filed Sept. 3, 1924 2a .MJ 30 l A i e g' INVTORS f MX '2, agitated June i6, 1925.

UNITED STA-Tas PATENT OFFICE.

STANLEY E. JACOBS, OF BROOKLYN, AND LOUIS J. SCHMEHL, OF LARCHMONT, NEW YORK, ASSIGNORS TO STANLEY-EVERETT CORPORATION. OF NEW YORK, N. Y., A

CORPORATION F NEW YORK.

BHEOSTAT.

Application led September 3, 1924. Serial No.- 735,580,

To all 'whom t may concern:

`Be it known thatwe, SrANLEY E. JACas, a citizen o'f'ltlie United States, and a resident of Brooklyn, Kings County, and Stateof .New York, and Loms'l Scimmia, a citizen of the United States, and a resident of Larchmont, New York, Vin the county of Westchester, have invented certain new and useiiblmprovementsin Rhcostats, of which thefollowing is a s ecification.

This'linv'en'tion i'e ates to rlieostats, potentioineters and devices of like nature where variations in resistance are obtained by Vshiftiiig acontact arm over the coils of a re- 15 s'stance winding.

The objects of the invention arc to provide a device of the character referred to in which the resistance winding and-the contact making elements will be fully ro'tected `from dust, 'moisturefand the possi ility of accidental sliort-circuiting, which will be ofv 4s'tibstantial and inexpensive con- 4 simple', 'struction arid 'at the same time present a bet- `ter an'dmore finished a, pearance and which furthermore willfbe o?) small size, coixpact design and have' incorporated in it, A ple and practical means for effecting Vernier gdjustments. The 'novel features of construction, combination .and relation of; parts by which all the foregoin and other o jects are attained Willapear groin the following specification.

In t e drawing accompanying and forming part of vthis specification2 simple and practical embodiments'of the invention are illustrated, wherein Figure 1 is a vertical sectional view of one of the rheostats mountedon a supporting panel.

21s a rear view of the rheostat.

Eigiire 3 is a'broken front elevation of the rheostat as it appears .removed from the Panel.

4 is an edge view of the devicev inoun on apanel and of modified form in the manner in which the supportin spider Serveis-,to space the rlieos'tat base bac ofthe p Figures 5 and 6 are sectional plan and side views respectively of the contact arm 'i0 and the friction washer for retaining the same iiiY variously adjusted relations.

Figure 7 is a combined view showing a modified form of contact arm both in plan and n side elevation.

The resistance is provided in the present disclosure by wound upon a substantially annular insulating core 8, disposed as the are of a circle about the central operating shaft 9.

10 :designates an insulating base for supporting conducting pai-ts of the device andv this base dilieis from the ordinary in that it. is made lin the form o f a hollow cup or shcllhaving :in internalcavity or insulatin chamber l1 for mechanically protecting an housing all of such electrical parts. The outside shape of this base is preferably of truncated conical forni, as indicated articulnl'ly inFigures 2 and 3,-so as to de eet and shed dust and moisture or other foreign matter and at the same time present a neat attractive appearance. At the center of the rear wall of the hollow base, a hub 12 is shown providing a bearing for the spindle,

which at this end is formed withxa head 13 'engagingover n spiing contact stri 14 held bythe binding post 15. This bin ing ost thus v-serves as the terminal for the adjustable switch arm and a second binding post lamounted like the first on the back Wall of theilhollow base is connected with one end off'the resistance coil.

a coil .of resistance wire 7:.

n annular resistance element is seatedin agroove or channel 17 formed in the rim of the hollow base and is held in place suiciently by being sprung into this seat and by the attachment of the one end of the resistance coil beneath the screw at the inner end of the binding post 16.

The contact arm is designated 18 and is shown constructed with an ungularly bent terminus 19 to ride over the outward portions of the resistance coils.

The Vernier effect -is obtained in the present invention by interposing a variable length of resistance wire between the contact arm and the spindle which forms part of the circuit connections. This additional resistance element is designtaed 20 and is shown as carried b an arcuate insulating support 21 mounte on a metallic hub 22 secured on the spindle 4by set screw 23, one

end of such Wiiie being caught between the.

insulating support and metallic. hub, as indicated'at 24:.

The insulating support 42l. is provided at opposite ends, of the arcuate portion with stop shoulders `25 positioned Afor engagement with the upstanding portion 26 of the contact arm and the .contact arm carries an upst'anding spring tongue 2'( for sliding engagement over the arcuate portion ofthe wlre.

Thisspring contact tongue may be formed as an integral part of the contact arm by being struck up out of the material of the arm, as indicated most clearly in Figures' 5- and 6, but if fgreater resiliency is desired, a separate piece of lighter spring metal may be mounted overtl1e contact arm, as shown -keyed to the base by an inwardly o at 28 in Figure 7, said overlying spring element having an upstanding contact, 'rtion 29 and lugs 30 bent down over the of the contact arm so that the same. will trav erse said contact arm; Y

The contact arm is' mounted within th'e hollow base so that it may vremain at rest while-the vernier arm is being adjusted by4 a .pivotal engagement over a reduced or shouldered portion 31 of the bearing hub 12 and it is fiictionally held in its adjusted positions by an overlyinfrfriction washer 32 rojecting lug 33 engaging in a scat 34 in ie side of the pivotal su port 31. This washer is secured in this keyed relation by the hub of the vernier arm, as shown in Figure 1, which is fixed to the spindle and the spring con-v necting. strip 14 acting on the head of the s indle serves to apply a spring, tension to t e vernier arm, friction washe'i and contact arm so thatV all three will be yieldingly retained in their` positions of adjustment, but at the same time can be readily shifted.

Formounting the rheostat on the back of a panel or theflike, a `three armed spider or plate 35 is shown secured at 36 across the open front of the hollow base and provided A with a hollow screw stud 37 providing a front bearing for the spindle and adapted when extended through the .panel 38 to're ceive a lock nut 39. After mountin the rheostat in this way, a suitable kno .or operating handle 40 may be secured on the projecting end of the spindle.

In Figures loto the ends ofthe spider or mounting plate are shown as seated in notches 41 formed in the rim of the base so as to lie flush with the rim and thus permit the hollow base to bedrawn up tight against the back of the panel. The front of the rheostat then becomes closed against the access of dust andthe like, so that the contacting parts are kept clean and -all possibility of accidental shorbcircuitingjby dropping Wires or the' like' is positively prevented.

To prevent overheatin 'simply securing the supportin of the resistance wire when`th`e hollow ase is thus entirely closed Aat the front, a Ventilating opening or openings 42 may be. provided in the back wallof the base, which wall is shown in Figv ures 1 and`2 as'snnk forwardlyintothe base and, protected by a raised riml 43 which acts as a glllard -for such openings. v

In `igure 4 the ventilation or additional ventilation. 1s afforded by spacing the rim of the hollow base'back of the panel to leave Van opening or o 'nings 44 between 'the rear of the anel an the edgeof the base. This effect 1s obtainedin the illustration "by the face of the rim instead o lseating it in the rim as in the first views.

The structure is simple, relatively inex-V and can be easily assembled without pensive the exercising of any special skill. Afterassembly, the parts can be readilyl inspected at the open side of the cup sha base, but

vvhenthe rheostat is moun 1n position plate 35 over for use, 'all the active parts are covered and 4 fully protected, while at -the same/time :proper ventilation is ,aordedj.preventoverheating. s y

This feature of proteetiongis particularly. importanti-when the device is used for radio and other foreign .matter lodging on there- Apurposes as it has beenifound that "dust,

sistance coils introduces variations and mii-.- teriall aects operation of the tubes controlle by the rheostat. .The spindle being held under spring tension'aets to yieldingly 'j l hold the vernier and contact-arms m any set relation and when adjustments "are required these are made' smoothly and easily bIv simply turning the one knob which serves t uough the lost motion or pick-upf con# nection to shift both the vernier arm. and

main contactarlo. sually'thevernier wire 20 will; have a resistance substantiall equal towme turn of the resistance coil 'so'A finest possibleadplstments 'are attalimble.v

That is claimpd 1s: o

, ilo 1. In a device o f the character disclosed, ai hollow cup shaped base of insulatinginaterial open at the front' andtfemprising 'aback wall with-a forwardlyeirteiidmg annul bx the annular rim bus ing for sfeatl g 1n an opening in the 2 back 5 seated in the 8 dudan a hollowcup shaped base of insulating ma-i nular rim,

covered by com rising extending anan annular resistance element hollow ofthe base enclosed and the forwardly extending rim,

a contactarm for engagement with the resistance element mounted within the hollow of the base and also enclosed and protected front. of the base for sup on the back of avpanel or and means at said open porting the device the like, said means including a plate Secured across the open fro t of the base panel or other support.

' 3,. In a device of the c a hollow cup shaped hase of terial open at the front wall `with-a forwardly and provided with a screw haracter disclosed,

insulating maand comprising a extending annular run, an annular resistance element seated in the hollow ofthe base enclosed and cov# ered by the forwardly extending rim, a confor engagement element mounted within base and also enclosedan annular riin, means at the base for supporting .baclvof a panel or the li of the ing for or other support and a the contact arm journ bushing and in the back comprising a hollow with the resistance the hollow of the d protected by the theo en front of the ke,

evice on the said means ina plate secured across the open front ase and provided with-a screw bush seating in an opening in the panel spindle for actuating aled in said screw wall of the hollow -the character discup shaped base. said base secured across the open front of the Same, an annular resistance element seated within the hollow hase behind said, supporting plate, a spindle journaled in the base and projecting through said supporting tact arm for engagement plate and a conwith the resistance ,element mounted within the hollow base and adapted to be actuated from the spindle, the

supporting plate being s rirn of the hollow base to cated` flush in the thereby enable the rim of the base to engage the back of a panel foncomplctely closing the front of the base. v

5. In a device of the a back wall vannular rim,

ably mounted ducting strip extending dlganannular resistance character disclosed, a hollow cup shaped insulating base having with a forwardly extending a spindle slidingly and rotatin said back wall and having an externally located head. nal posts on said back wall,

external termia spring confrom one of said ad of the spincoil seated within ""the hollow base and having one end connected with the other ter tact arm for engagement mina] post, a conwith the resistance coi-l mounted within the hollow base and means on the spindle for operating said contact arm.

6. In a device of the a hollow cup shaped insulating base having a back wall with a forwardly extending annular rim, a spindle slidingly and rotatably mounted in saidback wall and having an externally located head, external terminal posts on said back wall, a spring conducting strip extending,Y from one of said terminal posts beneath the head of the spindle, an annular resistance coil seated within vthe hollow base and having one end connected with the other terminal post, a contact arm for engagement with the resistancecoil mounted Within the hollow base and means on the spindle for operating said contact arm, said means including a Vernier arm fixed to the spindle and having a pick-up connection with the contact arm.

7'. In a device of the character disclosed, a hollow cup shaped insulating hase having a back wall with a forwardly extending ancharacter disclosed,

Vernier arm connection with the contact arm, said contact arm being journaled on the back wall of the base and a friction washer interposed between the contact arm and Vernier aim and'held nonrotatably to the base.- 8. In'aevice of the character disclose-d, an :annular resistance element, a swinging contact arm engaging the same, a concentrically tnounted vernier :irrn having an arcuate portion and shoulders at opposite ends of the same for pick-up engagement with the contact arm, a resistance eiement on the arcuate portionof the Vernier arm, a spring element on the contact arm having sliding engagement with resistance and -a nonrotata'ole separator between the contact and Vernier arme.

9.,In 'adevice of the character disclosed, a hollow base comprising a bac-k wall with the arcuate Vernier a forwardly extending annular rim, 'a y back wall, a prosurrounding said having a bushing fixed o n `the-spindle, a

Vernier element carried bysaid vernier armv igidin4 electrical circuit with the contact arm and aresistance element in the base engaged by the contact arin.

10. In a device of the character disclosed,

a supporting plate provided with a screw,

bushing by which the samemay be mounted on a panel, a hollow insulating-base secured Ato said plate, a spindle extending through the screw bushing into the base, a resistance' av supporting plate provided with a screwbushing b which thesame may be mounted on a pane a hollow insulating base secured to said plate, a spindle extending through the screw bushing into the base, a resistance element mounted withi'ngthe. hollow hase` a contact arm jfor engagementwith resistan'ce element and also mounted within -the base and "means on said spindle foractuating lsaid contact arm, including a Vernier arm in electrical contact with and having a pick-up connection with'the contact arm.

obase-comprising a back wall of insulating for said resistance' element exposed at the back of said 'insulating base for wiring pur- 12. In a. device of the character disclosed,

material and'an annular wall extending forwardly therefrom to form a hollow enclosing structure and an annular resistance clement seated in said hollow base and enclosed by the` forwardly extending rim, a support for the base connected with said forwardly extending rim, a shaft extending through said support into the hollow base, a movable contact connected with said shaft )within the hollow base in cooperating relation lto the annular resistance element and terminals on the insulating back wall connected with the resistance element-within the base and exposed on the back of the hollow base for 45 wiring purposes. Y 13. 'In a device of the character disclosed,

an insulating base, an annular resistance ele-A ment seated in said base, wiring terminalsposes, a plate attached to the front of the insulating base and provided with .a screw bushing for seating in a panel or other sup;

port, a-shaft journaled in said screw :bush- 5 ing and a contact arni actuated by saidf'shaft i Afor cooperationwith the annular 'resistance el ement.'

In witness wlier'eoLwe have hereunto set our hands this 28th day of August, 199A.

STANLEY E. JACOBS.

LOUIS J. SCHMEHL. 

